_version_ 1866915658454794240
author Dey, Lankeswar
Jennings, Ross J.
Taylor, Jackson D.
Glaser, Joseph
McLaughlin, Maura A.
Agazie, Gabriella
Anumarlapudi, Akash
Archibald, Anne M.
Arzoumanian, Zaven
Baker, Paul T.
Brook, Paul R.
Cromartie, H. Thankful
Crowter, Kathryn
DeCesar, Megan E.
Demorest, Paul B.
Dolch, Timothy
Ferrara, Elizabeth C.
Fiore, William
Fonseca, Emmanuel
Freedman, Gabriel E.
Garver-Daniels, Nate
Gentile, Peter A.
Good, Deborah C.
Hazboun, Jeffrey S.
Jones, Megan L.
Kaplan, David L.
Kerr, Matthew
Lam, Michael T.
Lazio, T. Joseph W.
Lorimer, Duncan R.
Luo, Jing
Lynch, Ryan S.
McEwen, Alexander
McMann, Natasha
Meyers, Bradley W.
Ng, Cherry
Nice, David J.
Pennucci, Timothy T.
Perera, Benetge B. P.
Pol, Nihan S.
Radovan, Henri A.
Ransom, Scott M.
Ray, Paul S.
Schmiedekamp, Ann
Schmiedekamp, Carl
Shapiro-Albert, Brent J.
Stairs, Ingrid H.
Stovall, Kevin
Susobhanan, Abhimanyu
Swiggum, Joseph K.
Wahl, Haley M.
author_facet Dey, Lankeswar
Jennings, Ross J.
Taylor, Jackson D.
Glaser, Joseph
McLaughlin, Maura A.
Agazie, Gabriella
Anumarlapudi, Akash
Archibald, Anne M.
Arzoumanian, Zaven
Baker, Paul T.
Brook, Paul R.
Cromartie, H. Thankful
Crowter, Kathryn
DeCesar, Megan E.
Demorest, Paul B.
Dolch, Timothy
Ferrara, Elizabeth C.
Fiore, William
Fonseca, Emmanuel
Freedman, Gabriel E.
Garver-Daniels, Nate
Gentile, Peter A.
Good, Deborah C.
Hazboun, Jeffrey S.
Jones, Megan L.
Kaplan, David L.
Kerr, Matthew
Lam, Michael T.
Lazio, T. Joseph W.
Lorimer, Duncan R.
Luo, Jing
Lynch, Ryan S.
McEwen, Alexander
McMann, Natasha
Meyers, Bradley W.
Ng, Cherry
Nice, David J.
Pennucci, Timothy T.
Perera, Benetge B. P.
Pol, Nihan S.
Radovan, Henri A.
Ransom, Scott M.
Ray, Paul S.
Schmiedekamp, Ann
Schmiedekamp, Carl
Shapiro-Albert, Brent J.
Stairs, Ingrid H.
Stovall, Kevin
Susobhanan, Abhimanyu
Swiggum, Joseph K.
Wahl, Haley M.
contents Free-floating objects (FFOs) in interstellar space$-$rogue planets, brown dwarfs, and large asteroids that are not gravitationally bound to any star$-$are expected to be ubiquitous throughout the Milky Way. Recent microlensing surveys have discovered several free-floating planets that are not bound to any known stellar systems. Additionally, three interstellar objects, namely 1I/'Oumuamua, 2I/Borisov, and 3I/ATLAS, have been detected passing through our solar system on hyperbolic trajectories. In this work, we search for FFOs on hyperbolic orbits that pass near millisecond pulsars (MSPs), where their gravitational influence can induce detectable perturbations in pulse arrival times. Using the NANOGrav 15-year narrowband dataset, which contains high-precision timing data for 68 MSPs, we conduct a search for such hyperbolic scattering events between FFOs and pulsars. Although no statistically significant events were detected, this non-detection enables us to place upper limits on the number density of FFOs as a function of their mass within our local region of the Galaxy. For example, the upper limit on the number density for Jupiter-mass FFOs ($\sim 10^{-2.5} - 10^{-3.5}~M_{\odot}$) obtained from different pulsars ranges from $5.25\times10^{6}~\text{pc}^{-3}$ to $5.37\times10^{9}~\text{pc}^{-3}$, while the upper limit calculated by combining results from all the pulsars is $6.03\times10^{5}~\text{pc}^{-3}$. These results represent the first constraints on FFO population derived from pulsar timing data.
format Preprint
id arxiv_https___arxiv_org_abs_2507_19475
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The NANOGrav 15-year Data Set: Search for Gravitational Scattering of Pulsars by Free-Floating Objects in Interstellar Space
Dey, Lankeswar
Jennings, Ross J.
Taylor, Jackson D.
Glaser, Joseph
McLaughlin, Maura A.
Agazie, Gabriella
Anumarlapudi, Akash
Archibald, Anne M.
Arzoumanian, Zaven
Baker, Paul T.
Brook, Paul R.
Cromartie, H. Thankful
Crowter, Kathryn
DeCesar, Megan E.
Demorest, Paul B.
Dolch, Timothy
Ferrara, Elizabeth C.
Fiore, William
Fonseca, Emmanuel
Freedman, Gabriel E.
Garver-Daniels, Nate
Gentile, Peter A.
Good, Deborah C.
Hazboun, Jeffrey S.
Jones, Megan L.
Kaplan, David L.
Kerr, Matthew
Lam, Michael T.
Lazio, T. Joseph W.
Lorimer, Duncan R.
Luo, Jing
Lynch, Ryan S.
McEwen, Alexander
McMann, Natasha
Meyers, Bradley W.
Ng, Cherry
Nice, David J.
Pennucci, Timothy T.
Perera, Benetge B. P.
Pol, Nihan S.
Radovan, Henri A.
Ransom, Scott M.
Ray, Paul S.
Schmiedekamp, Ann
Schmiedekamp, Carl
Shapiro-Albert, Brent J.
Stairs, Ingrid H.
Stovall, Kevin
Susobhanan, Abhimanyu
Swiggum, Joseph K.
Wahl, Haley M.
High Energy Astrophysical Phenomena
Free-floating objects (FFOs) in interstellar space$-$rogue planets, brown dwarfs, and large asteroids that are not gravitationally bound to any star$-$are expected to be ubiquitous throughout the Milky Way. Recent microlensing surveys have discovered several free-floating planets that are not bound to any known stellar systems. Additionally, three interstellar objects, namely 1I/'Oumuamua, 2I/Borisov, and 3I/ATLAS, have been detected passing through our solar system on hyperbolic trajectories. In this work, we search for FFOs on hyperbolic orbits that pass near millisecond pulsars (MSPs), where their gravitational influence can induce detectable perturbations in pulse arrival times. Using the NANOGrav 15-year narrowband dataset, which contains high-precision timing data for 68 MSPs, we conduct a search for such hyperbolic scattering events between FFOs and pulsars. Although no statistically significant events were detected, this non-detection enables us to place upper limits on the number density of FFOs as a function of their mass within our local region of the Galaxy. For example, the upper limit on the number density for Jupiter-mass FFOs ($\sim 10^{-2.5} - 10^{-3.5}~M_{\odot}$) obtained from different pulsars ranges from $5.25\times10^{6}~\text{pc}^{-3}$ to $5.37\times10^{9}~\text{pc}^{-3}$, while the upper limit calculated by combining results from all the pulsars is $6.03\times10^{5}~\text{pc}^{-3}$. These results represent the first constraints on FFO population derived from pulsar timing data.
title The NANOGrav 15-year Data Set: Search for Gravitational Scattering of Pulsars by Free-Floating Objects in Interstellar Space
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2507.19475